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Hi. Just thinking about laying underfloor heating on a college project, but wanted to avoid concrete for a screed on a timber cassette floor. BUT I still want to keep the thermal mass that it could bring (I'm thinking of a stone floor above the screed).
I see that sand is used as an external screed, but has anyone come across its use internally? I think it might provide some good sound insulation too, and allow easier access to pipes should there be any problems.
I've googled this, but nothing is jumping out at me (wrong search terms?).
Any thoughts as to why I shouldn't do this - assuming I get all the joints properly sealed..?
Sand was traditionally used. Sometimes over cellars, they put sand on rough sawn planks fixed to joists and then stone flags on top. Sand can be compacted using a wacker plate.
The thing you need to look out for is deflection in the timber sub floor causing cracking of screed. Having said that, if it were just compacted sand, that should move quite nicely.
Check out "Screedflor dB" http://www.screedflo.co.uk/db/index.html
They use a givlon type screed as well as a resilient layer to give separating floor performance, and have thermal mass. The screedflo system can include underfloor heating as well.
Thanks too Timber. I've taken a look at the systems, and they still rely on a setting screed as far as I can see - which I assume bonds. I wasn't completely explicit in the initial post - as I was just after experience - but I'm looking to see how far I can get to a Cradle to Cradle type building and I liked the idea of simply being able to sweep the screed away when I'm done with it.